Air conditioner for vehicle

ABSTRACT

Provided is an air conditioner for a vehicle which can prevent the controls over cooling cycle and heating cycle from interfering with each other and thereby prevent hunting between the cooling and heating cycles even when a compressor is operated to perform the heating cycle in an overlapping temperature range where air cooling and air heating are both required. An air conditioner ( 4 ) for a vehicle includes a refrigerant circulation circuit ( 9   b ) for air heating to circulate a refrigerant, and a control unit ( 29 ) to selectively perform a normal air conditioning mode in which a normal cooling operation is feasible by circulating the refrigerant through a refrigerant circulation circuit ( 9 a) for air cooling and an auxiliary heating mode in which an auxiliary heating operation is performed by circulating the refrigerant through the refrigerant circulating circuit ( 9   b ) for air heating.

TECHNICAL FIELD

The present invention relates to an air conditioner for a vehicle toheat the air in a vehicle interior using the heat from a cooling water.

BACKGROUND ART

A conventional vehicle air conditioner is generally comprised of an airheating unit using the heat from an engine cooling water and an aircooling unit using a refrigeration cycle.

In the air heating unit, a high-temperature engine cooling water havingabsorbed heat from the engine is circulated inside a heater core in aninstrument panel to heat the air by the heat from the heater core andblow the heated air from an outlet of the instrument panel for heatingthe air in the vehicle interior.

However, since the air heating unit uses the engine cooling water, thetemperature of the cooling water remains low for a while after an enginestart so that the air temperature blown to the vehicle interior is alsolow.

Thus, it may take a certain length of time for the air temperature ofthe vehicle interior to reach a temperature at which occupants can feelcomfortable.

In view of solving the above problem, Patent Document 1 discloses aknown air heating technique, for example.

According to the invention recited in Patent Document 1, the enginecooling water is heated with a heat pump and supplied to the heater coreuntil the engine cooling water becomes sufficiently high in temperaturefor use in heating the air. Thereby, warm air can be introduced into thevehicle interior even immediately after the engine start.

Meanwhile, in the above air cooling unit the high pressure refrigerantcompressed in the compressor is inflated in an evaporator in theinstrument panel to cool down the air around the evaporator byendothermic reaction of the inflated refrigerant. Thereby, the cooledair can be introduced from the outlet of the instrument panel into thevehicle interior to cool there.

Thus, the air cooling unit of the conventional vehicle air conditionergenerally cools the air in the vehicle interior by the refrigerationcycle of refrigerant.

Moreover, an airconditioning system for a vehicle is known, whichincludes air cooling and air heating cycles and shares a refrigerantpassage for the air cooling and heating cycles.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Patent Application Publication No. 08-310227

Patent Document 2: Japanese Patent Application Publication No.2003-80935

Patent Document 3: Japanese Patent Application Publication No.2005-206014

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, the vehicle air conditioner having the air cooling and heatingcycles may have a problem that when the compressor is operated forheating air in an overlapping temperature range of both of the aircooling and heating, hunting may occur between the air cooling andheating cycles due to the two opposite cycle controls' interfering witheach other.

The present invention aims to provide an air conditioner for a vehiclewhich can control the air cooling and air heating not to interfere witheach other and prevent hunting when the compressor is operated forheating air in an overlapping temperature range of the air cooling andheating.

Means to Solve the Problem

In view of achieving the above object, an air conditioner for a vehicleaccording to claim 1 of the present invention comprises a refrigerantcirculation circuit for air cooling to circulate a refrigerant through acompressor, a refrigerant condenser provided outside a vehicle interior,a first inflator means, an evaporator for air cooling provided in thevehicle interior, and an accumulator for vapor-liquid separation in thisorder; a cooling water circulation circuit for air heating to circulatea cooling water between a cooling water passage in a heat generator of avehicle drive unit and a heater core in the vehicle interior; athree-way solenoid valve provided between the compressor and thecondenser; and a refrigerant circulation circuit for air heating tocirculate a refrigerant through the compressor, the three-way solenoidvalve, a heat exchanger means for heating a cooling water, an outsideheat exchanger unit including a second inflator means and theaccumulator in this order, the heat exchanger means for heating acooling water comprising a heat exchanger for a cooling water providedin a middle of the cooling water circulation circuit for air heating,and an outside heat exchanger provided in a middle of the refrigerantcirculation circuit for air heating to transfer heat with the heatexchanger for a cooling water, and a control means to selectivelyexecute a normal airconditioning mode and an auxiliary air heating modeby a switching control of the three-way solenoid valve to switch toeither of the refrigerant circulation circuits for air cooling and forair heating, the normal air conditioning mode in which the refrigerantis circulated for normal cooling operation in the refrigerantcirculation circuit for air cooling, the auxiliary air heating mode inwhich the refrigerant is circulated for auxiliary air heating operationin the refrigerant circulation circuit for air heating.

According to claim 2 of the present invention, the air conditionerrecited in claim 1 further comprises a water temperature sensor fordetecting a temperature of the cooling water, an outside air temperaturesensor for detecting an outside temperature of the vehicle interior, andan inside air temperature sensor for detecting an inside temperature ofthe vehicle interior, wherein the control means is configured toselectively execute the normal airconditioning mode and the auxiliaryair heating mode on the basis of a condition of the cooling watertemperature, outside air temperature, and inside air temperature.

According to claim 3 of the present invention, the air conditionerrecited in claim 1 further comprises an air conditioner switch to startthe normal airconditioning mode, and an auxiliary air heating switch tostart the auxiliary air heating mode, wherein the control means isconfigured to switch the normal airconditioning mode to the auxiliaryair heating mode when the auxiliary air heating switch is turned on innon-air cooling operation.

According to claim 4 of the present invention, the airconditioneraccording to claim 2 further comprises an air conditioner switch tostart the normal airconditioning mode, and an auxiliary air heatingswitch to start the auxiliary air heating mode, wherein the controlmeans is configured to control operation of the compressor to perform anormal air cooling when the outside air temperature becomes equal to orover a predetermined air cooling start temperature in a coolingoperation of the normal airconditioning mode, and to switch the normalairconditioning mode to the auxiliary air heating mode when theauxiliary air heating switch is turned on in non-air cooling operationand when the outside air temperature is equal to or below apredetermined air heating start temperature and the cooling watertemperature becomes equal to or below a predetermined heating starttemperature.

According to claim 5 of the present invention, the air conditionerrecited in claim 1 can operate in a refrigerant recovery mode in which aremnant refrigerant in the condenser and the evaporator is recovered inthe accumulator, in switching to the auxiliary air heating mode afterthe cooling operation.

According to claim 6 of the present invention, the air conditionerrecited in claim 5, further comprises a memory in which anairconditioning control state of the vehicle air conditioner is storedat a stop of the vehicle drive unit.

Effects of the Invention

According to claim 1 of the present invention as thus configured, thevehicle air conditioner can operate in the auxiliary air heating mode inwhich refrigerant is circulated through the refrigerant circulationcircuit for air heating. Because of this, it can introduce warm air intothe vehicle interior even immediately after the start of the vehicledrive unit by supplying to the heater core the cooling water heated bythe heat exchanger means for heating cooling water while the vehicledrive unit's cooling water temperature is rising enough for the airheating after the vehicle drive unit starts.

According to claim 2 of the present invention, the vehicle airconditioner can selectively execute the normal airconditioning mode andthe auxiliary air heating mode on the basis of the condition of not onlythe outside and inside air temperatures but also the cooling watertemperature. Because of this, it can introduce warm air into the vehicleinterior even immediately after the start of the vehicle drive unit bysupplying to the heater core the cooling water heated by the heatexchanger means for heating cooling water while the vehicle drive unit'scooling water temperature is rising enough for the air heating after thevehicle drive unit starts.

Further, according to claim 3 of the present invention, the vehicle airconditioner is configured to be switched to the auxiliary air heatingmode only when the auxiliary air heating switch is turned on in thenormal airconditioning mode but not in the air cooling operation. Thiscan prevent hunting between the air cooling and air heating cycles sincethe normal airconditioning mode is performed with priority when thecompressor is driven for the air heating in an overlapping temperaturerange in which air heating and air cooling are both required.

According to claim 4 of the present invention, the vehicle airconditioner can selectively execute the normal airconditioning mode andthe auxiliary air heating mode on the basis of the condition of not onlythe outside and inside air temperatures but also the cooling watertemperature. Because of this, it can introduce warm air into the vehicleinterior even immediately after the start of the vehicle drive unit bysupplying to the heater core the cooling water heated by the heatexchanger means for heating cooling water while the vehicle drive unit'scooling water temperature is rising enough for the air heating after thevehicle drive unit starts.

Further, according to claim 5 of the present invention, in switching tothe auxiliary air heating mode after the air cooling operation, thevehicle air conditioner can operate in the refrigerant recovery mode inwhich the remnant refrigerant in the condenser and evaporator isrecovered in the accumulator. Therefore, it can efficiently use therefrigerant in the auxiliary air heating and efficiently perform airheating. Besides, the compressor can be free from a shortage oflubricant.

Further, according to claim 6 of the present invention, the vehicle airconditioner includes the memory to store the airconditioning controlstate of the vehicle air conditioner at stop of the vehicle drive unit.Accordingly, it can determine whether or not to need to operate in therefrigerant recovery mode when the vehicle drive unit is restarted toresume the air heating operation or whether or not to restart the airheating control of the vehicle air conditioner from the beginning orfrom the stop point of the vehicle drive unit on the basis of thecooling water temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an air conditioner for a vehicle according tothe present invention.

FIG. 2 schematically shows an airconditioning unit of the vehicle airconditioner.

FIG. 3 is a block diagram of a control system of the vehicle airconditioner including a control unit.

FIG. 3A is a flowchart for the main control by the control unit of thevehicle air conditioner.

FIG. 3B is a flowchart for the auxiliary air heating mode of the controlunit of the vehicle air conditioner.

FIG. 3C is a flowchart for the rotation control over the compressor bythe control unit of the vehicle air conditioner.

FIG. 3D is a flowchart for the discharge pressure control over thecompressor by the control unit of the vehicle air conditioner.

FIG. 3E is a timing chart for the control by the control unit of thevehicle air conditioner.

FIG. 3F is a timing chart for the control by the control unit of thevehicle air conditioner.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiment of the present invention will be described withreference to the accompanying drawings.

Embodiment <Overall Structure>

FIG. 1 shows a vehicle (automobile) interior 1, an engine compartment 2,a water cooled engine (vehicle drive unit) 3 provided in the enginecompartment 2, and an air conditioner for vehicle 4 according to thepresent invention.

The engine 3 includes a water jacket (not shown).

The water jacket has an engine cooling water passage (cooling waterpassage) around a combustion chamber (heat generator) of the engine 3.The cooling water is circulated through this passage to absorb the heatfrom the combustion chamber of the engine 3 and cool the engine 3.

An instrument panel (not shown) is provided on the front side of thevehicle interior 1. An airconditioning unit 5 constituting the vehicleair conditioner 4 is provided in the instrument panel.

<Structure of Airconditioning Unit 5>

In FIG. 2 the airconditioning unit 5 includes a blower unit 6, a coolerunit 7, and a heater unit 8.

An air passage 5 a is formed in the cooler unit 7 and the heater unit 8to connect them.

The air from the blower unit 6 is flowed through the air passage 5 a.

The blower unit 6 includes a fan (blower) 6 a and an intake unit 6 b.

The intake unit 6 b includes an outside air inlet 6 b 1, an inside airinlet 6 b 2, and an intake door 6 c.

The intake door 6 c is driven by a door drive unit (door drive means) 6c 1 comprising a motor to adjust the opening and closing or the openinglevel of the outside air inlet 6 b 1 and the inside air inlet 6 b 2.

The door drive unit 6 c 1 is controlled to change the stop position ofthe intake door 6 c to adjust the opening level of the outside air inlet6 b 1 and the inside air inlet 6 b 2 or open/close either of them.Thereby, the ratio of air intake amounts from the outside and inside ofthe vehicle interior can be changed.

The air from the intake unit 6 b is transmitted to the cooler unit 7 bythe fan (blower) 6 a.

The cooler unit 7 includes an evaporator for air cooling 7 a and an airpassage adjusting door 7 b at upstream of the evaporator 7 a (or betweenthe fan 6 a and the evaporator 7 a).

The air passage adjusting door 7 b is driven by a door drive unit (doordrive means) 7 b 1 comprising a motor to open and close the lower partof the air passage 5 a.

An air cooling refrigerant can be circulated inside the evaporator 7 a.During the refrigerant circulation, the air blown from the fan 6 a iscooled down while passing an air passage (not shown) of the evaporator 7a.

The air having passed through the air passage of the evaporator 7 a istransmitted to the heater unit 8.

The heater unit 8 includes a heater core for air heating 8 a, an airbypass passage 8 b, a mix door 8 c, and a mix chamber 8 d.

The air bypass passage 8 b, mix door 8 c, and mix chamber 8 d are formedat the side (downside in FIG. 2), near upstream side, and at downstreamside of the heater core 8 a, respectively.

The mix door 8 c is driven by a door drive unit (door drive means) 8 c 1comprising a motor.

The door drive unit 8 c 1 is controlled to change the stop position ofthe mix door 8 c to adjust the opening level of the upstream side airpassage of the heater core 8 a and the bypass passage 8 b or open orclose either of them. Thereby, the ratio of air amounts flowing throughthe air passage (not shown) of the heater core 8 a and flowing throughthe air bypass passage 8 b can be adjusted.

By closing the upstream of the heater core 8 a with the mix door 8 c,the air blown from the cooler unit 7 flows through the air bypasspassage 8 b, bypassing the heater core 8 a.

The mix chamber 8 d at downstream of the heater core 8 a includes aplurality of air outlets 8 e which are connected with a defrost grill, avent grill, and a foot grill of the vehicle interior, respectively.

Inside the heater core 8 a the engine cooling water can be circulated.The air from the blower unit 6 is heated while passing the heater core 8a when a high-temperature cooling water is circulated therein.

<Structure of Refrigerant Circulation Circuit>

The vehicle air conditioner 4 in FIG. 1 includes a refrigerantcirculation circuit 9 and a cooling water circulation circuit 10.

The refrigerant circulation circuit 9 includes refrigerant circulationcircuits for air cooling 9 a and for air heating 9 b.

The refrigerant circulation circuit 9 a is for air cooling refrigerationcycle while the refrigerant circulation circuit 9 b is for heat pumpcycle for heating the cooling water by the refrigerant.

<Structure of Refrigerant Circulation Circuit 9 a>

The refrigerant circulation circuit 9 a includes a compressor 11 forrefrigerant, a refrigerant pipe 11 a for air cooling and a condenser 12for refrigerant.

The refrigerant outlet of the compressor 11 is connected to one end ofthe air cooling refrigerant pipe 11 a while the other end thereof isconnected to the condenser 12 for refrigerant disposed outside thevehicle interior 1.

A power transmitter means (not shown) is provided between the compressor11 and the engine 3 and includes an electromagnetic clutch CL, a pulley(not shown), a belt (not shown), and else.

The compressor 11 is driven by the rotation of the engine 3 via thepower transmitter means.

The structure of the power transmitter means is well known, therefore, adetailed description thereof is omitted.

The refrigerant circulation circuit 9 a further includes a liquid tank13, an air cooling refrigerant pipe 13 a, a first inflator means 14, andthe evaporator 7 a.

The refrigerant inlet of the liquid tank 13 is connected to therefrigerant outlet of the condenser 12 and the refrigerant outletthereof is connected to one end of the air cooling refrigerant pipe 13a. The other end of the air cooling refrigerant pipe 13 a is connectedto the refrigerant inlet of the first inflator means 14 and therefrigerant outlet of the first inflator means 14 is connected to theevaporator 7 a.

The first inflator means 14 is specifically an expansion valve or anorifice formed by narrowing the passage of the air cooling refrigerantpipe 11 a.

The first inflator means 14 is configured to detect the temperature andpressure of the refrigerant from the refrigerant outlet of theevaporator 7 a and adjust the amount of liquid refrigerant flowing intothe refrigerant inlet of the evaporator in accordance with a load.

That is, the first inflator means 14 adjusts the amount of liquidrefrigerant flowing into the refrigerant inlet of the evaporator 7 a soas to emit the refrigerant from the refrigerant outlet thereof in anoverheated state at predetermined temperature/pressure.

The first inflator means 14 can adopt a known structure, therefore, adetailed description thereof is omitted.

The refrigerant circulation circuit 9 a further includes an air coolingrefrigerant pipe 7 a 1, a check valve 15, an air cooling refrigerantpipe 15 a, and an accumulator 16 for vapor-liquid separation.

One end of the air cooling refrigerant pipe 7 a 1 is connected to therefrigerant outlet of the evaporator 7 a while the other end thereof isconnected to the refrigerant inlet of the check valve 15. Therefrigerant outlet of the check valve 15 is connected to one end of theair cooling refrigerant pipe 15 a and the other end thereof is connectedto the accumulator 16 for vapor-liquid separation. The refrigerantoutlet of the accumulator 16 is connected to the refrigerant inlet ofthe compressor 11.

The refrigerant from the compressor 11 is circulated through the aircooling refrigerant pipe 11 a, condenser 12, liquid tank 13, air coolingrefrigerant pipe 13 a, first inflator means 14, evaporator 7 a, aircooling refrigerant pipe 7 a 1, check valve 15, air cooling refrigerantpipe 15 a, and accumulator 16 in this order, and returns to thecompressor 11.

Thus, the cycle in which the refrigerant is circulated in therefrigerant circulation circuit 9 a is a first refrigeration cycle.

In the first refrigeration cycle gaseous refrigerant is compressed bythe compressor 11 to become a high-temperature, high-pressure gaseousrefrigerant. Then, it releases its own heat to ambient air in thecondenser 12 to be cooled and condensed and turns to high-pressureliquid refrigerant and it is temporarily stored in the liquid tank 13and inflated to be liquid refrigerant in the first inflator means 14.

The low-pressure liquid refrigerant inflated by the first inflator means14 is supplied to the evaporator 7 a, and vaporized therein to turn togaseous refrigerant.

Thus, while vaporized in the evaporator 7 a, the low-pressure liquidrefrigerant absorbs heat from the air in the air passage 5 a.

This gaseous refrigerant passes through the air cooling refrigerant pipe7 a 1, check valve 15, air cooling refrigerant pipe 15 a, andaccumulator 16, and returns to the compressor 11.

<Structure of Refrigerant Circulation Circuit 9 b>

The refrigerant circulation circuit 9 b includes the compressor 11, athree-way solenoid valve 17, a bypass refrigerant pipe 17 a, and anoutside heat exchanger 18 for heating cooling water.

The three-way solenoid valve 17 is disposed in the middle of the aircooling refrigerant pipe 1 la and the outside heat exchanger 18 isdisposed outside the vehicle interior 1.

A branched refrigerant outlet of the three-way solenoid valve 17 isconnected to one end of the bypass refrigerant pipe 17 a and the otherend thereof is connected to the refrigerant inlet of the outside heatexchanger 18.

The refrigerant circulation circuit 9 b further includes a bypassrefrigerant pipe 18 b, an outside heat exchanger 18 a, and a secondinflator means 19.

One end of the bypass refrigerant pipe 18 b is connected to therefrigerant outlet of the outside heat exchanger 18 while the other endthereof is connected to the outside heat exchanger 18 a. The secondinflator means 19 is connected to the refrigerant outlet of the outsideheat exchanger 18 a.

The outside heat exchanger 18 a and the second inflator means 19 areprovided outside the vehicle interior 1.

The refrigerant circulation circuit 9 b further includes an outside heatexchanger 20 for refrigerant vaporization, a bypass refrigerant pipe 20a, a check valve 21, and the accumulator 16.

The outside heat exchanger 20 is supplied with the refrigerant inflatedby the second inflator means 19.

One end of the bypass refrigerant pipe 20 a is connected to therefrigerant outlet of the outside heat exchanger 20 while the other endthereof is connected to the refrigerant inlet of the check valve 21. Therefrigerant outlet of the check valve 21 is connected to the middle ofthe air cooling refrigerant pipe 15 a connecting the refrigerant outletof the check valve 15 and the accumulator 16.

The outside heat exchanger 18 a and the outside heat exchanger 20 areintegrally provided and referred to as an outside heat exchanger unit23.

The refrigerant is emitted from the compressor 11, passes through thethree-way solenoid valve 17, bypass refrigerant pipe 17 a, outside heatexchanger 18, bypass refrigerant pipe 18 b, outside heat exchanger 18 a,second inflator means 19, outside heat exchanger 20, bypass refrigerantpipe 20 a, check valve 21, and accumulator 16 in this order, and returnsto the compressor 11.

The refrigeration cycle in which the refrigerant is circulated in therefrigerant circulation circuit 9 b is a second refrigeration cycle.

According to the vehicle air conditioner 4, the refrigerant circulationcircuit 9 a of the first refrigeration cycle and the refrigerantcirculation circuit 9 b of the second refrigeration cycle are connectedin parallel relative to the compressor 11.

That is, the refrigerant circulation circuit 9 b is a bypass passage ofthe refrigerant circulation circuit 9 a.

Therefore, the outside heat exchangers 18, 18 a, 20 and else aredisposed on the bypass passage.

<Structure of Cooling Water Circulation Circuit 10>

The cooling water circulation circuit 10 is comprised of a water jacketpassage of the engine 3, a cooling water circulation passage 24, and theheater core 8 a.

The cooling water from the outlet of the water jacket is transmitted bya water pump (not shown) to the heater core 8 a through the coolingwater circulation passage 24 and returned to the passage of the waterjacket from the heater core 8 a.

The cooling water circulation passage 24 includes the passage of thewater jacket of the engine 3, a cooling water passage 24 a, and acooling water passage 24 b.

One end of the cooling water passage 24 a is connected to the coolingwater outlet of the water jacket while the other end thereof isconnected to the cooling water inlet of the heater core 8 a. The coolingwater outlet of the heater core 8 a is connected to one end of thecooling water passage 24 b, and the other end thereof is connected tothe cooling water inlet of the water jacket of the engine 3.

A heat exchanger for cooling water 25 is disposed in the middle of thecooling water circulation passage 24.

The heat exchanger for cooling water 25 includes a heat exchanger forcooling water 26 provided in the middle of the water passage 24 a and aheat exchanger for cooling water 27 provided in the middle of thecooling water passage 24 b.

A part of the cooling water passage 24 a is formed in the heat exchangerfor cooling water 26 while a part of the cooling water passage 24 b isformed in the heat exchanger for cooling water 27.

An outside heat exchanger 18 is disposed between the heat exchangers forcooling water 26, 27.

The heat exchangers for cooling water 26, 27, outside heat exchanger 18and else constitute a heat exchanger means for heating cooling water 28.

The heat exchangers 26, 27 for cooling water and the outside heatexchanger 18 are integrally provided to transfer heat therebetween.

Thereby, the engine cooling water in the heat exchangers for coolingwater 26, 27 is heated by the heat of the high-temperature,high-pressure gaseous refrigerant supplied from the compressor 11 to theoutside heat exchanger 18.

Deprived of heat by the engine cooling water, the high-temperature,high-pressure gaseous refrigerant is condensed inside the outside heatexchanger 18 to become a liquid refrigerant.

Also, the engine cooling water flowing from the heater core 8 a to thewater jacket is heated by the heat of the liquid refrigerant emittedfrom the outside heat exchanger 18.

<Structure of Control System Including Control Unit (Control Means)>

As shown in FIG. 3, the fan 6 a, compressor 11, and three-way solenoidvalve 17 are controlled by a control unit 29 such as an automaticamplifier to control the elements of the vehicle.

The control state of the vehicle air conditioner 4 is stored in a memory40.

The cooling water circulation circuit 10 of the vehicle air conditioner4 according to the present invention includes a water temperature sensor30.

The water temperature sensor 30 includes a signal communication system(not shown).

The water temperature sensor 30 detects the temperature of the coolingwater and outputs a detection signal indicating temperature information.

The detection signal is output from the water temperature sensor 30 tothe control unit 29.

In FIG. 3 the vehicle air conditioner according to the present inventionincludes an air cooling switch 31 and an air heating switch 32. ON/OFFsignals are output from the air cooling switch 31 and air heating switch32 to the control unit 29.

The water temperature sensor 30 is provided in at least one of thepassage of the water jacket of the engine 3 and the cooling watercirculation passage 24 to transmit detected temperature information tothe control unit 29 via the signal communication system.

The vehicle air conditioner 4 according to the present invention furtherincludes a intake temperature sensor 33, an inside air temperaturesensor 34, and an outside air temperature sensor 35 which are connectedto the control unit 29.

The intake temperature sensor 33 detects the temperature of airsuctioned into the airconditioning unit 5, the inside air temperaturesensor 34 detects the temperature of the vehicle interior 1, and theoutside air temperature sensor 35 detects the outside temperature of thevehicle interior 1.

The detection signals are output to the control unit 29 from the intaketemperature sensor 33, inside air temperature sensor 34, and outside airtemperature sensor 35.

The intake temperature sensor 33 is provided at upstream of the airpassage of the evaporator 7 a while the inside air temperature sensor 34is provided inside the instrument panel.

However, the positions of the intake temperature sensor 33 and insideair temperature sensor 34 should not be limited to the above positions.

Further, the vehicle air conditioner 4 according to the presentinvention includes a refrigerant pressure sensor 36.

The refrigerant pressure sensor 36 is provided in the air coolingrefrigerant pipe 11 a connecting the compressor 11 and the three-waysolenoid valve 17.

The refrigerant pressure sensor 36 is connected to the control unit 29to output a refrigerant pressure detection signal indicating refrigerantpressure information thereto.

The refrigerant pressure sensor 36 between the compressor 11 andthree-way solenoid valve 17 can detect the pressure of refrigerantemitted from the compressor 11 irrespective of the switch position ofthe three-way solenoid valve 17.

Further, the vehicle air conditioner 4 according to the presentinvention includes a rotation speed sensor 37.

The rotation speed sensor 37 is connected to the control unit 27 tooutput a rotation speed detection signal indicating rotation speedinformation of the compressor 11 thereto.

The vehicle air conditioner 4 according to the present inventionincludes an air conditioner switch (A/C switch) 38 and an auxiliary airheating switch 39.

The air conditioner switch 38 and auxiliary air heating switch 39 areconnected to the control unit 29 to output ON/OFF signals thereto.

In FIGS. 3E, 3F the auxiliary air heating switch 39 is a heat boosterswitch (HBS).

[Function of Control Unit 29]

The control unit 29 controls the electromagnetic clutch CL of theabove-described power transmitter means to intermittently connect/shutdown (ON/OFF) according to the ON/OFF signals of the air cooling and airheating switches 31, 32, detections signals of the intake temperaturesensor 33, inside air temperature sensor 34, outside air temperaturesensor 35, and water temperature sensor 30, and the rotation speeddetection signal of the rotation speed sensor 37, to drive/stop thecompressor 11. Thereby, it controls the vehicle air conditioner 4 toadjust the temperature of the vehicle interior 1.

Note that the air cooling switch 31 and air heating switch 32 can beturned on and off not only by manipulation of an occupant of the vehiclebut by the control unit 29.

[Manual Airconditioning Mode (I) and Automatic Airconditioning Mode(II)]

The vehicle air conditioner 4 is operated in an air cooling operationmode (A) for normal cooling operation and an air heating operation mode(B).

Also, the vehicle air conditioner 4 can be operated in either of amanual airconditioning mode (I) and an automatic airconditioning mode(II) in which the air cooling operation mode (A) and air heatingoperation mode (B) are switched manually or automatically, respectively.

In the manual airconditioning mode (I) the control unit 29 automaticallycontrols the vehicle air conditioner 4 to cool the air upon the turningon of the air cooling switch 31, and heat the air upon the turning-on ofthe air heating switch 32.

The control unit 29 performs the control on the basis of the detectedoutside temperature of the vehicle interior 1 (outside air temperature),the detected temperature of the vehicle interior 1 (inside temperature),and the target temperature (set temperature) of the vehicle interior.

The vehicle air conditioner 4 according to the present embodiment is setto be able to cool the air when the outside air temperature is a lowerlimit air cooling temperature (for example, −5 degrees C.) or more andto be able to heat the air when it is an upper limit air heatingtemperature (for example, 10 degrees C.).

The lower limit air cooling temperature and upper limit air heatingtemperature are changeable and not limited to the above values as −5 or10 degrees C.

Further, the air cooling operation mode (A) and air heating operationmode (B) can be switched by a mode selection switch or else instead ofthe air cooling switch 31 and air heating switch 32.

In the automatic airconditioning mode (II) the control unit 29automatically controls the vehicle air conditioner 4 to adjust thetemperature of the vehicle interior 1 to the target temperatureaccording to information on the outside and inside temperatures of thevehicle interior 1.

In the vehicle air conditioner 4 according to the present embodiment thecontrol unit 29 is configured to automatically turn on and off the aircooling switch 31 and air heating switch 32 on the basis of informationon the outside and inside temperatures of the vehicle interior 1.

The control unit 29 controls the air cooling switch 31 and air heatingswitch 32 to turn on and off on the basis of information on the vehicleelements and the on/off state of the auxiliary air heating switch 39.

The information on the vehicle elements includes the temperaturedetection signals from the intake temperature sensor 33, inside airtemperature sensor 34, outside air temperature sensor 35, watertemperature sensor 30, the refrigerant pressure detection signal fromthe refrigerant pressure sensor 36, and the rotation speed detectionsignal from the rotation speed sensor 37.

The control unit 29 acquires information on the air intake temperaturein the airconditioning unit 5 according to the temperature detectionsignal of the intake temperature sensor 33, information on the airintake temperature in the vehicle interior 1 according to thetemperature detection signal of the inside air temperature sensor 34,and information on the outside air temperature of the vehicle interior 1according to the temperature detection signal of the outside airtemperature sensor 35.

With the lower limit air cooing temperature (for example −5 degrees C.)and upper limit air heating temperature (for example 1 degrees C.) setas above, in the range between the two temperatures there is anoverlapping temperature range in which both air heating and coolingoperations are feasible.

The control unit 29 controls the air conditioner to preferentiallyperform normal air cooling (later-described automatic air cooling andheating control) in the overlapping range.

[Function of Vehicle Air Conditioner 4]

Next, the function of the vehicle air conditioner 4 under the control ofthe control unit 29 is described.

In the manual airconditioning mode (I) and automatic airconditioningmode (II) the flow of the refrigerant does not change between the aircooling operation mode (A) and air heating operation mode (B).

By way of example, the flow of refrigerant in the air cooling andheating operation modes (A), (B) in the manual airconditioning mode (I)is described.

[Manual Airconditioning Mode (I)] [Air Cooling Operation Mode (A)]

Receiving the ON signal from the air cooling switch 31 after the startof the engine 3, the control unit 29 starts normal air cooling control.

Then, the control unit 29 controls the three-way solenoid valve 17 todisconnect the refrigerant outlet of the compressor 11 and the bypassrefrigerant pipe 17 a and connect the refrigerant outlet of thecompressor 11 and the refrigerant inlet of the condenser 12.

Next, the control unit 29 controls the door drive unit 8 c 1 of theheater unit 8 to close the upstream air passage of the heater core 8 awith the mix door 8 c, and controls the door drive means 6 c 1 of theintake unit 6 b to close the outside air inlet 6 b 1 of the intake unit6 b and open the inside air inlet 6 b 2 with the intake door 6 c.

The control unit 29 controls the fan 6 a to suction the air from thevehicle interior 1 via the inside air inlet 6 b 2.

The suctioned air passes through the air passage 5 a, the air passage inthe evaporator 7 a, the air bypass passage 8 b of the heater unit 8 andthe mix chamber 8 d and is blown from the outlet 8 e to the vehicleinterior 1.

Meanwhile, the control unit 29 controls the compressor 11 to startcompressing a gaseous refrigerant.

Thereby, a high-temperature, high-pressure compressed refrigerant isemitted to the air cooling refrigerant pipe 11 a.

The compressed refrigerant is supplied to the condenser 12 through thethree-way solenoid valve 17 for cooling down and condensation and turnsto a liquid refrigerant.

The liquid refrigerant is accommodated in the liquid tank 13,thereafter, supplied to the first inflator means 14 through the aircooling refrigerant pipe 13 a and inflated and depressurized therein.

The depressurized liquid refrigerant is vaporized in the evaporator 7 ain the vehicle interior 1 and turns to a gaseous refrigerant.

This low pressure liquid refrigerant while being vaporized absorbs heatfrom the air flowing in the air passage of the evaporator 7 a.

The cooled air is blown from the outlet 8 e to the vehicle interior 1 tocool the air in the vehicle interior 1, as described above.

At this point, the liquid refrigerant from the first inflator means 14is vaporized to a gaseous refrigerant and this gaseous refrigerant flowsthrough the air cooling refrigerant pipe 7 a 1, check valve 15, aircooling refrigerant pipe 15 a, and accumulator 16 and returns to thecompressor 11.

Thus, in the normal air cooling operation, the refrigerant flows asindicated by the arrow f1 to cool the air in the vehicle interior 1.

[Air heating Operation Mode (B)]

Upon turning-on of an ignition switch (not shown) of the vehicle tostart the engine 3, the water temperature sensor 30 detects thetemperature of the engine cooling water in the water jacket and outputsa temperature detection signal to the control unit 29.

Then, upon turning of the air heating switch 32 as an instruction tostart heating operation, the control unit 29 determines whether or notthe engine cooling water has reached a required temperature (settemperature) for heating the air in the vehicle interior 1 according tothe temperature detection signal from the water temperature sensor 30.

The set temperature can be set by a known temperature setting structureor method, therefore, a detailed description thereof is omitted.

Next, when determining that the engine cooling water has not reached theset temperature during an engine start period due to a low outside airtemperature in winter, the control unit 29 controls the three-waysolenoid valve 17 to disconnect the refrigerant outlet of the compressor11 and the refrigerant inlet of the condenser 12 and connect therefrigerant outlet of the compressor 11 and the bypass refrigerant pipe17 a of the bypass passage.

Even by operating the compressor 11, the refrigerant does not flow intothe condenser 12, liquid tank 13, first inflator means 14, evaporator 7a and else.

Then, the control unit 29 controls the door drive unit 8 c 1 of theheater unit 8 to drive the mix door 8 c to open the upstream of the airpassage of the heater core 8 a and controls the door drive unit 6 c 1 ofthe intake unit 6 b to drive the intake door 6 c to close the outsideair inlet 6 b 1 and open the inside air inlet 6 b 2 of the intake unit 6b.

Then, the control unit 29 drives the fan 6 a to suction the air in thevehicle interior 1 from the inside air inlet 6 b 2.

The suctioned air passes through the air passage 5 a, the air passage ofthe evaporator 7 a, the air passage (not shown) of the heater unit 8,and the mix chamber 8 d and is blown to the vehicle interior 1 from theoutlet 8 e.

Since the refrigerant is not supplied to the evaporator 7 a, the airemitted from the fan 6 a and passing through the air passage of theevaporator 7 a is not cooled by operating the compressor 11.

Meanwhile, the control unit 29 drives the compressor 11 to compress thegaseous refrigerant and emit this high-temperature, high-pressurecompressed refrigerant to the air cooling refrigerant pipe 11 a.

The compressed refrigerant passes through the three-way solenoid valve17, bypass refrigerant pipe 17 a, outside heat exchanger 18, bypassrefrigerant pipe 18 b, outside heat exchanger 18 a, second inflatormeans 19, outside heat exchanger 20, bypass refrigerant pipe 20 a, checkvalve 21, and accumulator 16 in this order and returns to the compressor11.

The compressed refrigerant is condensed, releasing heat in the outsideheat exchanger 18, to turn to a high-temperature, high-pressure liquidrefrigerant and it passes through the outside heat exchanger 18 a of theoutside heat exchanger unit 23, second inflator means 19, and outsideheat exchanger 20 in this order and is emitted from the outside heatexchanger 20 to the bypass refrigerant pipe 20 a.

Then, the heat of the liquid refrigerant flowing in the outside heatexchanger 18 a is absorbed by the refrigerant in the outside heatexchanger 20.

The heat deprived liquid refrigerant is supplied to the second inflatormeans 19 from the outside heat exchanger 18 a.

The liquid refrigerant is inflated and depressurized in the secondinflator means 19, flows into the outside heat exchanger 20 to bevaporized to turn to a gaseous refrigerant, absorbing heat emitted fromthe outside heat exchanger 18 a.

The vaporized gaseous refrigerant passes through the bypass refrigerantpipe 20 a, check valve 15, and accumulator 16, and returns to thecompressor 11.

Also, the engine cooling water from the water jacket of the engine 3passes through the heat exchanger for cooling water 26, heater core 8 a,and heat exchanger for cooling water 27 and returns to the water jacketof the engine 3.

While passing through the outside heat exchanger 18, heat from thecompressed refrigerant transfers between the outside heat exchanger 18and the heat exchanger for cooling water 26 to heat the engine coolingwater flowing to the heater core 8 a in the heat exchanger for coolingwater 26.

The compressed refrigerant also heats the engine cooling water flowingfrom the heater core 8 a to the water jacket in the heat exchanger forcooling water 27 by transferring heat between the outside heat exchanger18 and the heat exchanger for cooling water 27.

The heated engine cooling water by the outside heat exchanger 18 andheat exchanger for cooling water 26 is supplied to the heater core 8 aand warms the air in the air passage thereof. The warmed air is blown tothe vehicle interior 1 from the outlet 8 e to heat the vehicle interior1.

As functioned above, the heat of the high-pressure, condensed gaseousrefrigerant from the compressor 11 is absorbed by the cooling water inthe outside heat exchanger 18. Then, the heat is negated withvaporization heat of the low-pressure refrigerant in the outside heatexchanger unit 23 to generate a difference in the pressure of therefrigerants. Thereby, the cooling water can absorb only an amount ofheat equivalent to the power of the compressor, forming an idealrefrigeration cycle.

Thus, in air heating operation, the engine cooling water is heated bythe flow of refrigerant in air heating cycle as indicated by the arrowf2, to heat the air in the vehicle interior 1.

[Automatic Air Cooling and Heating Operation]

[Airconditioning Control of Vehicle Air Conditioner 4 in Engine StartPeriod after Engine 3 Stops for Long Time]

By manipulation of an ignition key (not shown) to activate the controlunit 29 and turning on an ignition switch IGN, the engine 3 startsoperating.

At the engine start in the activation of the control unit 29, thetemperature detection signals from the temperature sensors of thevehicle elements (intake temperature sensor 33, inside air temperaturesensor 34, outside air temperature sensor 35, water temperature sensor30), the refrigerant pressure detection signal from the refrigerantpressure sensor 36, the rotation speed detection signal from therotation speed sensor 37, the ON/OFF signal from the auxiliary airheating switch 39 are input to the control unit 29.

The control unit 29 starts controlling the air cooling and heatingoperation in accordance with the input signals.

Specifically, the control unit 29 controls the turning on and off of theair cooling switch 31 and air heating switch 32 and that of theelectromagnetic clutch CL in accordance with the input signals as shownin the flowcharts in FIG. 3A to FIG. 3D and the timing charts in FIG. 3Eto FIG. 3F.

First, referring to FIG. 3E, a control over the air conditioner switch38 and auxiliary air heating switch 39 to turn on at time t1 isdescribed.

Referring to FIG. 3F, a control over the air conditioner switch 38 andauxiliary air heating switch 39 to turn on at time t01 is described.

[Air Cooling and Heating Switching Control] <Step S1>

When the air conditioner switch 38 is turned on during the engine 3 inoperation, the control unit 29 determines whether or not the auxiliaryair heating switch 39 is turned on. When the switch is not on, itproceeds to step S7 and performs control in the normal airconditioningmode in which the auxiliary air heating mode is not operated. When theswitch is on, it proceeds to step S2.

<Step S2>

When the auxiliary air heating switch 39 is on, the control unit 29determines whether or not the initial temperature of the engine coolingwater is 65 degrees C. (set temperature) or more according to thetemperature detection signal from the water temperature sensor 30.

The control unit 29 proceeds to step S7 to perform control in the normalairconditioning mode when the initial temperature of the engine coolingwater is 65 degrees C. or more.

The control unit 29 proceeds to step S3 when it is less than 65 degreesC., as shown in at time t1 in FIG. 3E, for example.

<Step S3>

The control unit 29 acquires outside air temperature informationaccording to the temperature detection signal from the outside airtemperature sensor 35.

The control unit 29 turns on the air heating switch 32 and sets theswitch position of the three-way solenoid valve 17 to air heating whenthe outside air temperature is −5 degrees C. or less, as shown in timet02 to t04 in FIG. 3F.

Thus, the three-way solenoid valve 17 disconnects the refrigerant outletof the compressor and the refrigerant inlet of the condenser 12, andconnects the refrigerant outlet of the compressor 11 and the bypassrefrigerant pipe 17 a of the bypass passage.

At time t04 in FIG. 3F, when the outside air temperature exceeds −5degrees C., the control unit turns on the air cooling switch 31 and setsthe switch position of the three-way solenoid valve 17 to air cooling.

Thus, the three-way solenoid valve 17 connects the refrigerant outlet ofthe compressor and the refrigerant inlet of the condenser 12, anddisconnects the refrigerant outlet of the compressor 11 and the bypassrefrigerant pipe 17 a of the bypass passage.

As shown at and after time t04, air heating is required when the outsideair temperature is over −5 degrees C. and 10 degrees C. or less.

However, in a case where the air conditioner switch 38 is operated toset the switch position of the three-way solenoid valve 17 to aircooling, the control unit 29 takes priority of cooling operation toprevent hunting between the air cooling and heating of the vehicle airconditioner 4.

In proceeding to the step S3 from step S2, the control unit 29 turns offthe air cooling switch 31 and determines whether or not the vehicle airconditioner 4 is in the air cooling operation mode (A).

Determining that it is in the air cooling operation mode (A), thecontrol unit 29 proceeds to step S7 and performs control in the normalairconditioning mode.

Meanwhile, determining that it is not in the air cooling operation mode(A), the control unit 29 proceeds to step S4 and starts a refrigerantrecovery mode for auxiliary air heating operation.

<Step S4>

Here, at a stop of the air heating operation in the air heatingoperation mode (B), the refrigerant outlet of the compressor 11 and therefrigerant inlet of the condenser 12 are disconnected while therefrigerant outlet of the compressor 11 and the bypass refrigerant pipeof the bypass passage 17 a are connected.

If the amount of refrigerant remaining in the condenser 12 andevaporator 7 a of a large volume is small, no problem will occur in theair heating operation which has started by the control unit 29 after theair heating operation mode (B).

However, after a stop of the normal air cooling in the air coolingoperation mode (A), the refrigerant outlet of the compressor 11 and therefrigerant inlet of the condenser 12 are connected while therefrigerant outlet of the compressor 11 and the bypass refrigerant pipeof the bypass passage 17 a are disconnected.

In this state a large amount of refrigerant remains in the condenser 12and evaporator 7 a of a large volume.

When the control unit 29 is operated to start air heating operation, therefrigerant in the condenser 12 and evaporator 7 a cannot be used in theheat pump cycle for heating (air heating) the engine cooling water.

Further, continuation of the air heating or cooling operation with alack of refrigerant may cause a shortage of lubricant to the compressor.

In order to prevent these problems, the control unit 29 operates in therefrigerant recovery mode, proceeding to the step S4 after a stop of thenormal cooling operation in the air cooling operation mode (A).

In the refrigerant recovery mode the control unit 29 controls thethree-way solenoid valve 17 to maintain the connection of therefrigerant outlet of the compressor 11 and the refrigerant inlet of thecondenser 12 and the disconnection of the refrigerant outlet of thecompressor 11 and the bypass refrigerant pipe 17 a of the bypasspassage.

Further, proceeding to the step S4 after a stop of the air heatingoperation in the air heating operation mode (B), the control unit 29controls the three-way solenoid valve 17 to connect the refrigerantoutlet of the compressor 11 and the refrigerant inlet of the condenser12 and disconnect the refrigerant outlet of the compressor 11 and thebypass refrigerant pipe 17 a of the bypass passage.

Then, the control unit 29 turns on the electromagnetic clutch CL at timet1 in FIG. 3E (time t01 in FIG. 3F) to transmit the rotation of theengine 3 to the compressor 11.

Thereby, the compressor 11 is driven by the rotation of the engine 3 tostart compressing the refrigerant after time t1 in FIG. 3E (time t01 inFIG. 3F).

Here, the refrigerant is compressed in the normal air cooling in the aircooling operation mode (A) while the control unit 29 stops the fan 6 a.

Because of this, the refrigerant flows as indicated by the arrow f1 inthe normal cooling in the air cooling operation mode (A) and that in thecondenser 12 and evaporator 7 a is recovered in the accumulator 16.

The control unit 29 starts recovering the refrigerant in step S4 at timet1 in FIG. 3E (time t01 in FIG. 3F) and proceeds to step S5.

Note that the compressor 11 is a continuous variable displacementcompressor as disclosed in Patent Document 2, for example.

This continuous variable displacement compressor or the compressor 11 isa wobble plate type reciprocating compressor and the inclination of thewobble plate is controlled by electric signals from outside to change apiston stroke and adjust a discharge amount.

Therefore, the compressor 11 includes a control valve (not shown,hereinafter ECV) such as an electromagnetic valve which is controllableby electric signals from outside.

For example, with use of an electromagnetic valve as ECV communicatingwith the high-pressure side of the compressor 11, the low-pressure sidethereof and a crankcase are connected through a passage with apredetermined opening level, and the pressure in the crankcase istransferred to the low-pressure side of the compressor 11.

Accordingly, by adjusting the opening level of the electromagnetic valveto introduce or shut down the pressure in the high-pressure side of thecompressor 11, it is possible to control the pressure in the crankcaseand the discharge amount of the refrigerant from the compressor 11.

A duty signal with a predetermined duty value (discharge amount rate) isoutput from the control unit 29 to the electromagnetic valve.

The length of time in which the electromagnetic valve is opened isdecided according to a magnitude of the duty value to decide thedischarge amount of the compressor 11 accordingly.

The control over the ECV of the compressor 11 by a duty signal can berealized by a method disclosed in Patent Document 3 or else.

In the step S4 the compressor 11 is driven at a duty ratio of 100% tocontrol the ECV of the compressor 11.

Alternatively, the control unit 29 can omit the steps S4, S5 and proceedto step S6 when it proceeds to the step S4 after stopping the airheating in the air heating operation mode (B).

In view of this, the control unit 29 can be configured to acquire, at astart of its operation, the final control state of the vehicle airconditioner 4 in a previous operation from the memory 40.

<Step S5>

The control unit 29 starts the refrigerant recovery operation in therefrigerant recovery mode at time t01 in FIG. 3F, controls the three-waysolenoid valve 17 at time t02 to disconnect the refrigerant outlet ofthe compressor 11 and the refrigerant inlet of the condenser 12 andconnect the refrigerant outlet of the compressor 11 and the bypassrefrigerant pipe 17 a of the bypass passage, and sets the switchposition of the three-way solenoid valve to air heating.

Then, the control unit 29 turns off the electromagnetic clutch CL attime t02 and stops transmitting the power to the compressor 11 from therotation of the engine 3.

In this case the refrigerant in the condenser 12 and evaporator 7 a isrecovered in the accumulator 16 due to differences in pressure betweenthe condenser 12 and accumulator 16 and between the evaporator 7 a andaccumulator 16.

The control unit 29 determines whether or not a refrigerant recoverytime (time from turning off of the electromagnetic clutch CL at timet02) is a set time (for example, 30 seconds). When it has not reachedthe set time, the control unit returns to step S4 while determining thatit has reached the set time, the control unit proceeds to the auxiliaryair heating mode in step S6.

As shown in FIG. 3E, the temperature of the engine cooling watergradually rises over time after elapse of the set refrigerant recoverytime.

Further, the control unit 29 turns off the electromagnetic clutch CL attime t04 in FIG. 3F if the intake pressure of the compressor 11 is equalto or over a set pressure, to stop the operation of the compressor 11for a set time (for example, 10 seconds) so that the intake pressure ofthe compressor 11 is reduced to less than the set pressure.

As the discharge pressure of the compressor 11 gradually acts on theaccumulator 16, the intake pressure thereof is reduced, resulting inequalizing the pressure of the entire refrigerant passage.

Thus, with the equalization of the pressure of the entire refrigerantpassage and the smaller intake pressure than the set pressure, thecontrol unit 29 can operate the compressor 11 again without a suddenincrease in the intake pressure thereof exceeding the set pressure.

Therefore, at time t05 the control unit 29 turns on the electromagneticclutch CL to transmit the rotational power of the engine 3 to thecompressor 11 to drive it.

At the outside air temperature being over −5 degrees C., the controlunit 29 equalizes the pressure of the entire refrigerant passage asabove, turns off the air conditioner switch 38 at time t06, and changesthe switch position of the three-way solenoid valve 17 to air heatingfrom air cooling to recover the refrigerant due to a pressure differenceas above until time t07 (for 30 seconds from time t06, for example).

[Control in Auxiliary Air heating Mode (Heat Booster Mode)]

<Step S6>

The control unit 29 turns on the electromagnetic clutch CL at time t03to drive the compressor 11 and start controlling the vehicle airconditioner 4 in the auxiliary air heating mode.

Herein, “electromagnetic valve: ON (air heating)” in step S6 of FIG. 3Asignifies that the auxiliary air heating is made feasible by controllingthe three-way solenoid valve 17 to disconnect the refrigerant outlet ofthe compressor 11 and the refrigerant inlet of the condenser 12 andconnect the refrigerant outlet of the compressor 11 and the bypassrefrigerant pipe 17 a of the bypass passage.

Likewise, “electromagnetic valve: OFF (air cooling)”in step S7 of FIG.3A signifies that the normal air cooling is made feasible by controllingthe three-way solenoid valve 17 to connect the refrigerant outlet of thecompressor 11 and the refrigerant inlet of the condenser 12 anddisconnect the refrigerant outlet of the compressor 11 and the bypassrefrigerant pipe 17 a of the bypass passage.

The control unit 29 can omit the refrigerant recovery in steps S4, S5 ifit is not needed and proceeds to the step S6, and turns on theelectromagnetic clutch CL at time t03 to drive the compressor 11.

The control unit 29 acquires the rotation speed of the compressor 11from the rotation detection signal from the rotation sensor 37, and whenit has reached 4,000 [rpm] at time t4, it decreases the rotation speedof the compressor 11 by turning off the electromagnetic clutch CL.

Meanwhile, the control unit 29 acquires the rotation speed of thecompressor 11 from the rotation detection signal from the rotationsensor 37, and when it is smaller than 3,500 [rpm] at time t5, itincreases the rotation speed of the compressor 11 by turning on theelectromagnetic clutch CL.

The control unit 29 acquires the rotation speed of the compressor 11from the rotation detection signal from the rotation sensor 37, and whenit is larger than 3,500 [rpm] at time t6, it decreases the rotationspeed of the compressor 11 by turning off the electromagnetic clutch CL.

Further, the control unit 29 acquires the temperature of the enginecooling water from the temperature detection signal from the watertemperature sensor 30, and when it has reached 70 degrees C., itdecreases the rotation speed of the compressor 11 by turning off theelectromagnetic clutch CL at time t2.

Meanwhile, the control unit 29 acquires the temperature of the enginecooling water from the temperature detection signal from the watertemperature sensor 30, and when it has reached 65 degrees C., itincreases the rotation speed of the compressor 11 by turning on theelectromagnetic clutch CL at time t3.

Moreover, in such auxiliary air heating operation the control unit 29controls the rotation and refrigerant discharge pressure of thecompressor 11 as shown in FIGS. 3C, 3D, respectively.

Next, referring to the flowchart in FIG. 3C, the rotation control overthe compressor 11 is described.

<Rotation Control of Compressor 11>

Under the control of the compressor 11 by the control unit 29, theminimum rotation speed thereof is set to 3,500 [rpm] and the maximumrotation speed to 4,000 [rpm].

The values of the minimum and maximum rotation speeds are changeddepending on the configuration of the compressor 11, therefore, theyshould not be limited to such values as 3,500 [rpm], 4,000 [rpm].

The rotation control of the compressor 11 during the auxiliary airheating by the control unit 29 is described with reference to FIG. 3Cunder such a condition by way of example.

<Step S6-1>

The control unit 29 acquires a change over time in the rotationdetection signal from the rotation sensor 37 and proceeds to step S6-2.

Herein, a state of the compressor 11 that the rotation speed is risingfrom the minimum rotation speed 3,500 [rpm] to the maximum rotationspeed 4,000 [rpm] is referred to as a state (1), and a state thereofthat the rotation speed is falling from the maximum rotation speed 4,000[rpm] to the minimum rotation speed 3,500 [rpm] is referred to as astate (2).

<Step S6-2>

The control unit 29 determines whether or not the compressor is in thestate (2), and when it is not in the state (2) but in the state (1), itproceeds to step S6-4, and when it is in the state (2), it proceeds tostep S6-3.

<Step S6-3>

The control unit 29 controls the three-way solenoid valve 17 to be“electromagnetic valve: ON (air heating)” to enable the auxiliary airheating, and turns off the electromagnetic clutch CL to stop therotation of the compressor 11.

Then, the control unit 29 deletes an integration value for the ECVcontrol of the compressor 11 and returns to step S6-1.

<Step S6-4>

The control unit 29 controls the three-way solenoid valve 17 to be“electromagnetic valve: ON (air heating)” to enable the auxiliary airheating, and turns on the electromagnetic clutch CL to drive thecompressor 11.

In this case the control unit 29 sets the duty ratio at 100% for the ECVcontrol and controls the compressor 11 to operate at the dischargepressure Pd of a target value 2,200 [kPa], and returns to step S6-1.

<Pressure Control of Compressor 11>

The control unit 29 allows the refrigerant pressure sensor 36 to detectthe discharge pressure of the compressor 11 and acquire a refrigerantpressure detection signal from the refrigerant pressure sensor 36.

The control unit 29 turns off the electromagnetic clutch CL to stop thecompressor 11 and decrease the discharge pressure Pd thereof when thedischarge pressure has reached 2,400 [kPa] at time t8 in FIG. 3E.

Meanwhile, the control unit 29 turns on the electromagnetic clutch CL todrive the compressor 11 and increase the discharge pressure Pd of thecompressed refrigerant when the discharge pressure has fallen to 1,600[kPaG] at time t9 in FIG. 3E.

In the vehicle air conditioner 4 according to the present embodiment,the minimum discharge pressure of the compressor 11 is set to 1,600[kPaG] and the maximum discharge pressure is set to 2,400 [kPaG] underthe control of the compressor 11 by the control unit 29.

The values of the minimum and maximum discharge pressures are changeddepending on the configuration of the compressor 11 so that they shouldnot be limited to such values as 1,600 [kPaG], 2,400 [kPaG].

Thus, the control unit 29 is configured to control the duty ratio of thecompressor 11 for the ECV control and the electromagnetic clutch CL toturn on and off so as to adjust the discharge pressure Pd to the targetdischarge pressure of 2,200 [kPaG].

Here, the duty ratio control of the compressor 11 for the ECV control isa proportional integral control.

Moreover, such pressure control is performed according to the flowchartin FIG. 3D to control the discharge pressure Pd of the compressor 11 tothe target discharge pressure of 2,200 [kPa].

<Step S6-5>

The control unit 29 acquires a change over time in the refrigerantpressure detection signal of the refrigerant pressure sensor 36 andproceeds to step S6-6.

Herein, a state of the compressor 11 that the discharge pressure isrising from the minimum discharge pressure 1,600 [kPaG] to the maximumdischarge pressure 2,400 [kPaG] is referred to as a state (1), and astate thereof that the rotation speed is falling from the maximumdischarge pressure 2,400 [kPaG] to the minimum discharge pressure 1,600[kPaG] is referred to as a state (2).

<Step S6-6>

The control unit 29 determines whether or not the discharge pressure ofthe compressor 11 is in the state (2). When it is not in the state (2)but in the state (1), it proceeds to step S6-8, and when it is in thestate (2), it proceeds to step S6-7.

<Step S6-7>

The control unit 29 controls the three-way solenoid valve 17 to be“electromagnetic valve: ON (air heating)” to enable the auxiliary airheating.

It turns off the electromagnetic clutch CL to stop the rotation of thecompressor 11.

Then, the control unit 29 deletes an integration value for the ECVcontrol of the compressor 11 and returns to step S6-5.

<Step S6-8>

The control unit 29 controls the three-way solenoid valve 17 to be“electromagnetic valve: ON (air heating)” to enable the auxiliary airheating.

It turns on the electromagnetic clutch CL to drive the compressor 11 andreturns to step S6-5.

The control unit 29 sets the duty ratio of the compressor 11 at 100% forthe ECV control and controls the compressor 11 to operate at thedischarge pressure Pd of the target value of 2,200 [kPa].

[Normal Air Cooling Operation] <Step S7>

When the outside air temperature exceeds 10 degrees C., the control unit29 controls the three-way solenoid valve 17 to connect the refrigerantoutlet of the compressor 11 and the refrigerant inlet of the condenser12 and disconnect the refrigerant outlet of the compressor 11 and thebypass refrigerant pipe 17 a of the bypass passage.

Also, the control unit 29 turns on the electromagnetic clutch CL andcontrols the normal air cooling operation in the air cooling operationmode (A).

[Airconditioning Control of Vehicle Air Conditioner 4 during StartPeriod after Short Stop of Engine 3]

Next, an airconditioning control of the vehicle air conditioner 4 whenthe vehicle stops during the air heating operation and the engine 3 isstopped and restarted to resume the operation is described.

The airconditioning control state of the vehicle air conditioner 4 atthe stop of the engine 3 is stored in the memory 40. Thereby, it ispossible not to recover the refrigerant for auxiliary air heating at therestart of the engine 3 and the air heating operation.

A state of the engine cooling water at stop of the engine 3 that it isrising in temperature from 65 to 70 degrees C. during air heatingoperation is defined to be a state (1) and a state that it is fallingfrom 70 to 65 degrees C. is defined to be a state (2).

These states are stored in the memory 40 at the stop of the engine 3,which makes it possible to determine whether the air heating control ofthe vehicle air conditioner 4 is performed from the beginning or fromthe engine stop point.

By restarting the air heating control of the vehicle air conditioner 4from the engine stop point, it is possible to shorten a length of timefor starting air heating in the vehicle interior 1.

In view of this, the control unit 29 controls the air heating operationfollowing the flowchart in FIG. 3B at a time when the engine 3 isoperated in a short time after the stop during the air heatingoperation.

Such air heating control is described in the following.

[Air heating and Cooling Switch Control]

<Step S10>

First, the control unit 29 determines whether or not the auxiliary airheating switch 39 is on in step S1 in FIG. 3A when the engine 3 isstarted by the ignition switch IGN and the air conditioner switch 38 isturned on. At the switch being not on, it proceeds to step S14 toperform control in the normal airconditioning mode and at the switchbeing on, it proceeds to step S11.

<Step S11>

The control unit 29 determines whether or not the air cooling switch 31is off or the vehicle air conditioner 4 is in the air cooling operation.

Determining that the vehicle air conditioner 4 is in the air coolingoperation mode (A), the control unit 29 proceeds to step S14 to performcontrol in the normal airconditioning mode.

Meanwhile, determining that the vehicle air conditioner 4 is not in theair cooling operation mode (A), the control unit 29 proceeds to stepS12.

<Step S12>

The control unit 29 determines whether or not the temperature of theengine cooling water is rising from 65 to 70 degrees C. during the airheating operation or in the state (1) at the stop of the engine 3. Inthe state (1) it proceeds to step S13 while not in the state (1) itproceeds to step S14.

<Step S13>

The control unit 29 performs the steps S6 in FIG. 3A, S6-1 to S6-4 inFIG. 3C, S6-5 to S6-8 in FIG. 3D, and returns to step S10.

<Step S14>

The control unit 29 proceeds to an auxiliary air heating completionstandby mode.

In the completion standby mode the control unit 29 controls thethree-way solenoid valve 17 to be able to shift to the normalairconditioning mode and proceeds to step S15.

In the completion standby mode the control unit 29 turns off theelectromagnetic clutch CL to stop the compressor 11.

At this point the control unit 29 does not perform duty control over theECV of the compressor 11 so that the duty ratio is 0%.

<Step S15>

The control unit 29 counts the time from start of the auxiliary airheating completion standby mode to the refrigerant discharge from thecompressor 11 and determines whether or not a predetermined time (forexample, 10 seconds) has elapsed.

With the predetermined time not elapsed, the control unit 29 returns tostep S14 and with the predetermined time elapsed, it proceeds to stepS16.

<Step S16>

The control unit 29 performs the step S7 in the normal airconditioningmode in FIG. 3B.

<Operational Effects of the Embodiment>

The thus-configured vehicle air conditioner 4 can operate in theauxiliary air heating mode in which refrigerant is circulated throughthe refrigerant circulation circuit 9 b for air heating, and selectivelyexecute the normal airconditioning mode and the auxiliary air heatingmode on the basis of the condition of not only the outside and insideair temperatures but also the cooling water temperature. Because ofthis, it can introduce warm air into the vehicle interior evenimmediately after the start of the engine 3 by supplying to the heatercore 8 a the cooling water heated by the heat exchanger means forheating cooling water 28 while the engine 3's cooling water temperatureis rising enough for the air heating after the engine starts.

Further, the vehicle air conditioner 4 according to the presentembodiment is configured to be switched to the auxiliary air heatingmode only when the auxiliary air heating switch 39 is turned on in thenormal airconditioning mode but not in the air cooling operation. Thiscan prevent hunting between the air cooling and air heating cycles sincethe normal airconditioning mode is performed with priority when thecompressor 11 is driven for the air heating in an overlappingtemperature range in which air heating and air cooling are bothrequired.

Further, in switching to the auxiliary air heating mode after the aircooling operation, the vehicle air conditioner 4 according to thepresent embodiment can operate in the refrigerant recovery mode in whichthe remnant refrigerant in the condenser 12 and evaporator 7 a isrecovered in the accumulator 16. Therefore, it can efficiently use therefrigerant in the auxiliary air heating and efficiently perform airheating. Besides, the compressor 11 can be free from a shortage oflubricant.

Further, the vehicle air conditioner 4 according to the presentembodiment includes the memory 40 to store the airconditioning controlstate of the vehicle air conditioner 4 at stop of the engine 3.Accordingly, it can determine whether or not to need to operate in therefrigerant recovery mode when the vehicle drive unit 4 is restarted toresume the air heating operation or whether or not to restart the airheating control of the vehicle air conditioner 4 from the beginning orfrom the engine stop point on the basis of the cooling watertemperature.

Although the present invention has been described in terms of exemplaryembodiments with reference to the drawings, it is not limited thereto.It should be appreciated that variations or modifications may be made inthe embodiments described by persons skilled in the art withoutdeparting from the scope of the present invention as defined by thefollowing claims.

In the present embodiment the cooling water is circulated, for coolingthe engine, in the water jacket passage (cooling water passage) providedaround the combustion chamber (heat generator) of the engine 3 (vehicledrive unit). Alternatively, it can be for an electric motor (vehicledrive unit) of a motor driven vehicle and circulated in the water jacketpassage (cooling water passage) provided in the housing (heat generator)of an electric motor for driving a vehicle.

Further, the cooling water can be used for cooling the heat generator ofa secondary battery and else other than an electric motor.

REFERENCE SIGNS LIST

1 vehicle interior

3 engine (vehicle drive unit)

4 vehicle air conditioner

7 a evaporator

8 a heater core

9 a refrigerant circulation circuit for air cooling

9 b refrigerant circulation circuit for air heating

10 cooling water circulation circuit for air heating

11 compressor

12 condenser

14 first inflator means

16 accumulator

17 three-way solenoid valve

18 outside heat exchanger

19 second inflator means

23 outside heat exchanger unit

25 heat exchanger for cooling water

28 heat exchanger means for heating cooling water

29 control unit (control means)

30 water temperature sensor

34 inside air temperature sensor

35 outside air temperature sensor

38 air conditioner switch

39 auxiliary air heating switch

40 memory

1. An air conditioner for a vehicle, comprising: a refrigerantcirculation circuit for air cooling to circulate a refrigerant through acompressor, a refrigerant condenser provided outside a vehicle interior,a first inflator means, an evaporator for air cooling provided in thevehicle interior, and an accumulator for vapor-liquid separation in thisorder; a cooling water circulation circuit for air heating to circulatea cooling water between a cooling water passage in a heat generator of avehicle drive unit and a heater core in the vehicle interior; athree-way solenoid valve provided between the compressor and thecondenser; and a refrigerant circulation circuit for air heating tocirculate a refrigerant through the compressor, the three-way solenoidvalve, a heat exchanger means for heating a cooling water, an outsideheat exchanger unit including a second inflator means and theaccumulator in this order, the heat exchanger means for heating acooling water comprising a heat exchanger for a cooling water providedin a middle of the cooling water circulation circuit for air heating,and an outside heat exchanger provided in a middle of the refrigerantcirculation circuit for air heating to transfer heat with the heatexchanger for a cooling water, and a control means to selectivelyexecute a normal airconditioning mode and an auxiliary air heating modeby a switching control of the three-way solenoid valve to switch toeither of the refrigerant circulation circuits for air cooling and forair heating, the normal air conditioning mode in which the refrigerantis circulated for normal cooling operation in the refrigerantcirculation circuit for air cooling, the auxiliary air heating mode inwhich the refrigerant is circulated for auxiliary air heating operationin the refrigerant circulation circuit for air heating.
 2. The airconditioner according to claim 1, further comprising: a watertemperature sensor for detecting a temperature of the cooling water; anoutside air temperature sensor for detecting an outside temperature ofthe vehicle interior; and an inside air temperature sensor for detectingan inside temperature of the vehicle interior, wherein the control meansis configured to selectively execute the normal airconditioning mode andthe auxiliary air heating mode on the basis of a condition of thecooling water temperature, outside air temperature, and inside airtemperature.
 3. The air conditioner according to claim 1, furthercomprising: an air conditioner switch to start the normalairconditioning mode; and an auxiliary air heating switch to start theauxiliary air heating mode, wherein the control means is configured toswitch the normal airconditioning mode to the auxiliary air heating modewhen the auxiliary air heating switch is turned on in non-air coolingoperation.
 4. The airconditioner according to claim 2, furthercomprising: an air conditioner switch to start the normalairconditioning mode; and an auxiliary air heating switch to start theauxiliary air heating mode, wherein the control means is configured tocontrol operation of the compressor to perform a normal air coolingoperation when the outside air temperature becomes equal to or over apredetermined air cooling start temperature in a cooling operation ofthe normal airconditioning mode, and switch the normal airconditioningmode to the auxiliary air heating mode when the auxiliary air heatingswitch is turned on in non-air cooling operation and when the outsideair temperature is equal to or below a predetermined air heating starttemperature and the cooling water temperature becomes equal to or belowa predetermined heating start temperature.
 5. The air conditioneraccording to claim 1, wherein the air conditioner can operate in arefrigerant recovery mode in which a remnant refrigerant in thecondenser and the evaporator is recovered in the accumulator, inswitching to the auxiliary air heating mode after the cooling operation.6. The air conditioner according to claim 5, further comprising a memoryin which an airconditioning control state of the vehicle air conditioneris stored at a stop of the vehicle drive unit.